Definition: In this task, you are given an input list A. You need to convert all the alphabets in the list with a number representing their position in the English alphabet. E.g., replace A by 1, B by 2, a by 1, b by 2, and so on.
Input: ['y', '3845', '3511', '1939', 'U', '4249']

25, 3845, 3511, 1939, 21, 4249